1. Field of the Invention
This invention deals with the method for producing vinyl-type conducting polymer fibers and vinyl-type conducting polymer fibers produced thereby, especially by electrospinning of a precursor of vinyl-type conducting polymer dissolved in volatile solvent and vinyl-type conducting polymer fibers produced thereby.
2. Description of the Related Art
The electrospinning is a method for producing fibers by application of a high voltage to polymer melt or solution. Since the electrospinning is capable of producing fibers with diameters between nano- and micrometers without exploiting vacuum and heating equipment, there are a number of reports in recent years.
For example, there are reports on electrospinning of polyacrylonitrile (PAN), poly(L-lactic acid) (PLA), and polyethyleneoxide (PEO). (Non-patent document 1: Takui Takahashi and Hidenori Okuzaki, “Fabrication of Functional Polymer Nanofibers by Electrospinning”, Engineering Materials, 51(9), 34-37, (2003)).
There are also reports demonstrating that the applied voltage, polymer concentration, distance between tip of the nozzle and the target, and shape of the tip of the nozzle are important for electrospinning of amorphous polymers such as polybutadiene, polystyrene-polybutadiene alloy, and widely-used polystyrene. (Non-patent document 2: Yoshihiro Yamashita, Akira Tanaka, and Frank Ko, “Characteristics of Elastomeric Nanofiber Membranes Produced by Electrospinning (1F05)”, Fiber Preprints, Japan, 59(1), 83 (2004)).
For other examples, electrospinning applied to copolymers, composites, organic-inorganic hybrid materials is also reported, and in recent years, there are reports on applications to catalysts, membranes for separation, sensors, materials for medical application, biomaterials, and drug delivery devices utilizing an extremely large surface area of the nanofabric produced by electrospinning.
The production method of fibers with diameters between several tens to several hundreds nanometers by electrospinning of natural Bombyx mori silk fibers is released in the Japanese Laid-open patent publication described below. Herein hexafluoroacetone hydrate is the most suitable solvent to produce recombinant hybrid silk fibers by electrospinning without reducing the molecular weight with superior mechanical properties of the silk or silk-like fibers, and which is achieved by electrospinning of a solution of silk or silk-like materials in air dissolved in this solvent. (Patent document 1: Japanese Laid-open patent publication No. 2004-068161) On the other hand, nanofibers of organic semiconducting materials such as poly(p-phenylenevinylene) (PPV) is necessary for the development of organic electronics in the next generation, such as organic electroluminescence, organic transistors, and organic solar cells. Although the production of fibers by electrospinning is the conventional technique as described above, the electrospinning of PPV to form fibers is considered to be impossible because of its infusible and intractable properties. There is also no report on producing PPV fibers by electrospinning.
If high conducting, mechanically high-strength, and stable fibers such as PPV were easily produced in a nanometer-size, the development of organic electronic devices in the next generation such as organic electroluminescence, organic transistors, and organic solar cells would be promoted. Furthermore, conducting polymers are expected as an antenna of IC tags and electrical wires of an existing IC tip instead of metals.